The partial dopamine receptor agonists (--)-3-PPP and transdihydrolisuride enhance prolactin secretion in female but not in male rats.

The effects exerted by the partial dopamine (DA) receptor agonists (--)-3-(3-hydroxyphenyl)-N-n-propylpiperidine [(--)-3-PPP] and transdihydrolisuride (TDHL) on prolactin secretion were compared in male and female rats. Both agents were found to increase prolactin release more than tenfold in female rats. In male rats, in contrast, (--)-3-PPP and TDHL were either without effect or decreased prolactin secretion. It is suggested that this sexually differentiated prolactin response to partial DA agonists reflects a lower responsiveness of lactotroph DA receptors in female than in male rats.